Principles of Photography- Aperture (Controlling Depth of Field)

In our Principles of Photography Workshop Series we try our best to share what we were able to teach ourselves about photography, in simple, easy-to-understand concepts. These are just some basics to help you get started, there is much more information to learn beyond these basics. But by understanding the most basic principles of photography then building upon them through practice, practice and more practice, you can capture the type of images that you want.

Note: Teaching and understanding photography can be often be complicated and confusing. Of course, there are many ways to explain these concepts & there is no “right” way to teach this. So if you think you can explain it better, then obviously you don’t need our help. Now, everyone grab your camera and let’s start figuring this stuff out together! And have fun!

Our last discussions were about Exposure, then Shutter Speed. Reading about these two concepts first will be helpful in understanding this whole series!

As mentioned in the previous post, Shutter Speed is about controlling motion with the amount of light entering your camera. Shutter Speed works in conjunction with Aperture to create the total Exposure of the photograph.

What is Aperture?

Aperture is about the AMOUNT, the amount of light that enters your camera through the lens “hole” or the “eye” of the camera.

Once the light enters the hole opening in the lens, it then enters your camer

What is the Aperture on your camera?

Just like the pupil in our eyes that open and close depending on the amount of light we see, the camera has an eye too, which is the Aperture.

When our eyes need more light, the pupil opens up (creates a bigger opening) to let in more light. When there is too much light, the pupil gets smaller (creates a smaller opening) to let in less light.

So, the Aperture does the exact same thing for the camera, but the Aperture “hole” opening lies within your lens.

(LEFT) f/1.4, the opening is big, lets a lot of light through (MIDDLE) f/5.6 , (RIGHT)f/16- the opening is small, lets less light through.

How is Aperture measured?

Aperture is measured in the size of the “hole” opening in the lens

Aperture is measured in a measurement called “f-stops”

The size of the aperture hole opening determines the f-stop number

The BIGGER the aperture hole opening, the MORE light comes in, which gives a SMALLER f-stop number.

The smaller f-stop numbers (such as 1.4, 2.8) let more light into the camera, and these numbers are considered “FAST”

So when you hear of terms like “fast lens”, “fast aperture”, “fast f-stop”, just know that means the lens is able to open up WIDE and letting more light coming in.

More confusing terms you will hear when describing the big hole opening: “Stop down your f-stop”, “wide aperture”, “open up your f-stop”. All that means is to let more light into the camera by opening up the aperture hole opening, which you do by making the number smaller.

The SMALLER the aperture hole opening, the LESS light comes in, which gives a BIGGER f-stop number

The bigger f-stop numbers (such as 6 or bigger) let less light into the camera, and these numbers are considered “SLOW”

So when you hear of terms like “slow lens”, “slow aperture”, “slow f-stop”, just know that means the lens hole is SMALLER and give you less light coming in.

More confusing terms you will hear when describing the smaller hole opening” “Stop up your f-stop”, “small aperture”, ” close your f-stop”. All that means is to let less light into the camera by closing up the aperture hole opening, which you do by making the number bigger.

Right! This is why everyone gets so confused and frustrated about understanding aperture!

It makes sense that the bigger the Aperture opening, the more light comes in, but why is the f-stop number smaller?

And, it makes sense that the smaller Aperture opening, the less light comes in, but why is the f-stop number bigger?

Answer- The bastards who set it only wanted to confuse everyone! Just kidding, it is actually in reference to the lens’ focal ratio, but we won’t get into it further because it will make your head spin. For now it may be more helpful to understand what the numbers do with the following little analogy:

Try understanding the f-stop number relationship this way:

Imagine your windows as the aperture on your camera (stand in front of your windows if this exercise helps), with the drapes hanging.

Pull all the drapes to the edges, more light comes in, right? So you just opened up the aperture “hole” opening, by letting in more light. Imagine the small f-stop number as the amount of drapes that is covering the hole.

So, you have LESS drapes covering the light coming in, the less drapes equals the SMALLER f-stop NUMBER!

Finally, imagine the f-stop number as the amount of coverage, covering up the light opening.

How to control Aperture?

Just like controlling the amount of light into your room by opening and closing the window shutters, you can control your Aperture and how much light enters your lens, then to your camera. Essentially controlling your Aperture is one part of controlling your total Exposure

Most camera’s will have a “Aperture Priority” function on your camera. You can choose your Aperture and make it fast or slow by turning the dial. Your camera will automatically adjust the rest of the exposure settings.

You can control it on “Manual”, but this will take more practice because you will have to manually control the rest of the exposure components (Shutter Speed and ISO).

Why would I want to understand Aperture? Isn’t it easier to just shoot on “auto” or “program” and let the camera do it all the thinking for me?

Certainly on most occasions, letting the camera do all the thinking for you will give you good results.

BUT, in order to take your photography to a higher level and more CREATIVE CONTROL, you must learn Aperture.

OK, so what exactly does this Aperture thing-y do? How will it give me more choices and creative control? – Answer: DEPTH of FIELD

The primary creative control of Aperture is to control the “Depth of Field”, which means how much of the image you want to be in focus.

By controlling the amount of light coming into the camera by the size of the Aperture hole opening, you control how much FOCUS you want.

When you’re photographing something with a NARROW or SHALLOW depth of field, that simply means that you want something specific to be in focus (only one part) and the rest to be kinda blurry.

When you’re photographing something with a WIDE or DEEP depth of field, that simply means that you want more of the picture to be in focus.

EXAMPLES of Aperture controlling your Depth of Field- how much you want to be in focus:

The tomato picture has very NARROW or SHALLOW depth of field because only a specific, selected point is in focus, where as the rest of the image is blurry.

Foreground: the single tomato and the wood in the very front of the image is sharp, in focus.

Midground: the cluster of tomatoes is less in focus, kinda blurry

Background: the tomato leaf, and basket of tomatoes is very blurry, out of focus.

This was shot intentionally so that the focus would be on the single tomato, bringing the perspective to the single tomato. Still pretty, isn’t it?

Egg & Pasta Image:

In the f/1.4 image, you can see how selective the focus is: only the quail eggs in the foreground are in focus.

As the f/stop closes to let less light in (number gets bigger), more of the image starts to come into focus.

In f/6.3, the brown eggs start to come into focus.

In f/16, everything is in focus: quail eggs, brown eggs and pasta.

(Bottom) You can see the obvious depth of field difference between the two extreme f-stops. The f/1.4 has a very shallow depth of field (only quail eggs in focus), vs. the f/16 which has a very wide depth of field (everything is in focus)

Dog Biscuits image:

The left shallow depth of field image has only the front doggie biscuit in focus.

When the f-stop is opened up wide, the ALL the doggie biscuits are in focus!

Our doggies love the wide depth field cause they can see ALL the doggie biscuits!

There are two main purposes to controlling Aperture:

Primary reason – to control how much of the image you want in focus for the photograph. By making the hole bigger (smaller f-stop numbers on camera=more shallow depth of field) or smaller (bigger f-stop numbers on camera=deeper depth of field), you can control the amount of FOCUS.

To adjust the Exposure when shooting in Manual. A faster f-stop, bigger hole (smaller number) will let in more light, and less of the image will be in focus. A slower f-stop, smaller hole (bigger number) will let in less light, and more of the image will be in focus.

Final Thoughts on Aperture: In order to really start understanding, you have to practice. Reading about it will only allow your brain to get so far.

Find the Aperture Priority Mode on your camera (some point & shoots may not have this option).

In Aperture Priority, you will be telling the camera what Aperture you want to shoot at, and it will adjust the rest to get what it thinks is the correct exposure (usually this will at least get you close to a decent exposure.)

Remember – Fast Aperture Number (1.4, 2, etc…aka wide aperture-recall it is a bigger hole opening) = More shallow depth of field

Your lens will limit how much you can open the aperture (how small the number will get). Some lenses won’t allow a very shallow depth of field.

If you do have a very fast lens (1.2, 1.4, etc…) and are shooting on those lower aperture numbers, the super shallow depth of field can make getting a good focal point tricky. The tip of the nose might be in focus and everything else starting to get blurry. It takes time & practice to shoot very shallow depth of fields well.

Many times in order to get a correct exposure, larger aperture number (bigger numbers ie. 13, 16) require a slow shutter speed. This can result in camera shake if you are not shooting on a tripod.

How to find out fast is your lens or the speed of our lens? The lowest f/stop number your lens can achieve is usually written on the barrel of the lens.

Now go shoot something and play with Depth of Field. Choose what you want in focus or choose it all to be in focus. Either way, there is no right or wrong. You have the creative control to decide what type of look you want for your photograph.

Whew! Is it time for another drink yet? We’re ready for it!

We know this is a lot of info to digest. Read it a few times, and try to understand at least the depth of field part. That will help you get more creative with your photography. By the time you go full manual, it helps to understand the full concept of aperture in order to use your camera fluidly, so don’t throw that part of it out of your brain just yet. Slowly build your understanding through practice and finding other ways people have explained it. All of us learn differently, so it helps to have exposure to different forms of teaching.

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Photography Series: Understanding these concepts one step at a time will help you capture the images that you want.

Just a year or so late finding your terrific material here…
And just having completed a 2-day so-called intensive on the SLR at Cooper Union that didn’t come close to informing this kind of material, I am so happy to have found you.
Thank you, thank you, thank you!!
Carolg

Inan – Thank you for the compliments. We definitely still plan to write about each of those topics, we’ve just been too busy at our studio to write the tutorials properly. Don’t know when we will be able to get to it, but it shall be done some time in the future.

That was a great tutorial! I must have read it about a dozen times I didn’t know anything about Aperture and Shutter speed before, but with this tutorial, I understand it a lot better…Like you said, “Practice, practice, practice”…Just got my first DSLR and I can’t wait to apply what i’ve learned…Thanks for sharing

So what is a general rule of thumb for the aperauture setting on a dinner plate? I statred with the 1.8, and it looks like only maybe 1/10 of the photo is in focus. At 3.5 it still isn’t looking good. Do I need to be closer to 7 to get most of a plate at a 15-30 angle of view in focus? Nothing looks right to me, would a 100mm get more in focus with a better background blur?

The depth of field is dependent of the relationship between the lens and aperture. Diff. focal length will have diff. depths of field at the same aperture. A micro (also known as a macro) lens will also have a more pronounced depth of field than a lens that isn’t a micro yet is still of the same focal length. Confusing huh? Best way is to shoot with the lens you like and adjust the aperture until you find the depth of field you like. This is what everyone refers to as “practice, practice, practice.” Soon you’ll start to know your equipment and can adjust to get what you want.
Keep closing down the aperture (make the number bigger) until you get what you want clean. 3.5 is still fairly shallow. Hit 6.4, 7.1 and see how you like them. Keep increasing the number to find what you like. That is the beauty of digital in that we get instant feedback. Zoom in on the image or tether, if you can, so you can see everything instantly.
A deeper focal length will change the perspective as well. If we shoot something with the 105mm vs the 50mm, the objects in the background and foreground will seem closer to the subject with the 105mm. If you have an assortment of lenses to shoot with, or can rent, play with them to see what you like better. A telephoto tends to compress the images, which is sometimes wanted and other times not. We’ll be doing a post on it to give a visual representation of what we mean. Hope this helps in the mean time.

Hi There,
Thanks for the tutorials – they are super easy to read and understand! I do have a question on DOF though: I’ve been told that using a telephoto lens gives pictures a very “flat” or “flattened” look. I _kind of_ understand, but am not really sure I’m getting the concept. So is this flat look a bad thing? Abnormal? To be avoided at all costs? I’d love to see a post or reply on this one..
Thanks again!

Your drape analogy makes total sense, it’s totally putting it all into perspective for me. I LOVE your simple explanations for the basics, and I am so excited for the rest of your series. Right now I am shooting with a crappy $100 dollar point and shoot. I accidentally put it through the washing machine, only for my hubby to bring it back to life in our food dehydrator! The camera has served me well (it must be natural talent…), but I am ready to take my photography to the next level. I’m pretty sure there will be a canon rebel waiting for me under the tree this year :). Your series has me keeping tabs on how to use it….

Thank you for your helpful lessons. They are all basic but very important information, especially to beginner like me. I read over and over so many time, word by word. Although it’s easy to understand but it’s not easy to remeber such as big number, small window…However, when I practice and get used to it, I start to enjoy taking photograph. I really appreciate your work as well as the way you explain your work. Just want to say thanks. Can’t wait for next lesson.

texasgirl- Thank you. The blurred background effect is the depth of field. Aperture controls the depth of field, and in the case of using a macro lens, the depth of field is further emphasized by the nature and construction of the lens. Macro lens have a more shallow depth of field than other lenses. The principle of Aperture controlling the depth of field is the same, only with a macro lens you are going from a super shallow depth of field to a somewhat shallow depth of field as you increase the aperture number; compared to a “regular” lens where you’ll go from a shallow depth of field to deep depth of field as you increase the aperture number. Hope that makes sense.

I’m not a member of this website however I’ve been reading all of your food posts throughout the year. Love all of your recipes and pictures. Thanks for the informative info on this post also! I am in the process of shopping for a SRL camera and would ask if you could recommend one? Canon, Nikon, etc.. Better yet, which brand and model do you happen to have? Thanks much!

Thank you! This is a huge help . I’m still trying to get used to auto/digital after using primarily SLR Pentax and Nikon. I’ve been wondering how to get that out-of-focus background, and you’ve explained it beautifully!

Holy moly! This is great. I was just about to go to sleep and then I thought “hmmm, I’ll stop by WORC and see what’s cookin’ ” when lo and behold it is a post with answers to photog questions I have been pondering for quite some time! When I am more awake I will be studying this for sure. Thanks for sharing so much of what you know! It’s so wonderful seeing that self-taught photography can lead to photos like yours. Appreciate the information immensely! –Rachael

You have no idea…this is the first time I’ve read something very clear and approachable f-stops/aperture. I’m a visual learner so your photos were really helpful for me. I’m about to dive into the dslr world, and am enjoying your series very much!

This is such great information to have. I just fiddle around with my camera and hope for the best. I’m not sure I want to invest in a photography course right now so having information like this at hand really helps. Thanks!

So far I’ve been enjoying reading all of your photography tips series. This is one of the best I’ve read for Aperture. I started to play with Aperture only during the summer. Now I set the Aperture first when I shoot a picture. Love the pictures with the comparaison between f/1.4 & f/16. A picture is worth a thousand words. Thanks! xx

So many tutorials on this subject make my eyes glaze over, but you have written an excellent, easy to understand explanation of a tricky subject. This is a wonderful series and I’ve found it very helpful.

white on rice: you’re right in that you’ve done a great job of keeping in layman’s (or woman’s) terms. You’re right that the cloudyness is sometimes aesthetically useful or pleasing and I’ve used it to that effect. I’m certain that if I had a full-frame camera (well I already use my film camera extensively), then I’d invest in the 50mm F1.4G. I’m not sure how the 35mm F1.8 pairs head-to-head with the 35mm F2 (which I use primarily), but I’ve been more than pleased with my F2 prime lens at the lowest apertures. But I do find that if I’m shooting more landscape-type photos, I’ll push the aperture to something like F/8 to get it as sharp as possible.

I think what you’re doing is great for casual and hobby photographers, especially food bloggers armed with SLRs. This way, they can get the most out of their (generally) very complex cameras. In a sense, I wish they made SLRs with LESS controls, and just the ones you really need. Like the controls that Leicas have, just the bare minimum. Even tiny point-and-shoots have features and options that 90% of people will virtually never use.

I like this piece because it covers a part of photography that is very difficult to understand for beginning photographers, but arms them with powerful tools to get the most out of their photography. One thing I’m trying to do more with my camera is increase aperture (to F/4 or F5.6) in ample light because sometimes depth-of-field is just too paper thin. Sometimes even parts of dishes are thrown out of focus, like the sides from the main ingredient. It seems to be a bigger problem with 50mm lenses on cropped sensors (75mm equiv). Do you see this as well? Anyways, I think sometimes food photographers overuse small DOF, and I’m beginning to see that very wide DOFs can look very cool as well, like those F/16 photos you’ve made.

ah you are teaching us all of your secrets one note as well with aperture, sharpness increases as you hit an “ideal” aperture for each lens, which is usually around F/8 or F/11 depending on the lens. Many lenses with lower aperture ratings tend to get very soft at F1.4. I find that Nikon’s F1.4D lens (and maybe even the G lens) is cloudy at F1.4, so there’s give and take when it comes to bringing your aperture to that figure. But great tutorial!

mattatouille- Hi Matt! Thanks! The information here aren’t secrets, it’s all common and basic information explained in very simple way to help as many beginners as possible. Yeah, there are many many more technical details about aperture that can be discussed, but like we said, this is just a simplified version.

As far as the “ideal” aperture for each lens, so many circumstances can attribute to that “cloudy” that you refer to and the same goes for achieving great sharpness at wide apertures such as 1.4. We’ve been able to capture some really crisp, sharp shots stopped way down by correcting other variables within the camera, lighting and set-up. It all depends on the camera body, sensor size, etc…
It is true that lenses are slightly less sharp at the lower aperture settings, and that as you increase the aperture number (many super geek reviews we’ve read often get the ideal clarity around as low as f/5.6) the sharpness will hit its prime. It is something which really depends on the optics of the individual lens. Although for nearly all of our lenses we shoot with, we would be hard pressed to say it was “very soft” at the lowest aperture settings. Most people aren’t going to be able to see it with the naked eye unless the image is blown up to bigger sizes. Often times this slight softening actually makes the photo a bit more visually appealing. Kind of like how HDTV’s super clarity isn’t always the most complimenting for real life.
The new 50mm 1.4 G series lens is quite wonderful, we haven’t had any sharpness issues with it when compared to our 35mm 1.8 . We highly recommend the Nikon 50mm, it’s the best for it’s money. It isn’t perfect. No. But is it still a great lens? We would have to say yes.
All this of course, is really technical talk, dealing with variables on specific equipment. This post is intended to be more about understanding the basic principles of aperture without making people bang their heads against the wall in confusion. We didn’t want to force in too many variables to increase an already bewildering subject.
Maybe when we have more time, we’ll share more details in our upcoming photography workshops!

Great post (and series)! I wish this had been around when I first got my DSLR (not that long ago). After reading a lot of tutorials, I finally got it enough to know which direction to adjust the aperture though it’s till confusing sometimes. But you guys did a great job of making it approachable and understandable.

This series is so timely for me! I’ve been working through a companion book to my DSLR and trying to wrap my head around everything. It’s been slow going. Your explanations are so easy to understand. I love the visual of likening the f stops to curtains–now THAT makes sense!!

I’m loving this series. I’ve been shooting mostly on AV setting for quite a while, but still didn’t completely understand this! Thanks for taking the time to prepare all the examples, beautifully done.

Like Jessica, I learned this all a long time ago, then pit down my SLR for a v long time. When I picked it up again, it was digital! I am having such a good time relearning the process without the expenditure and guess work of film processing. Thank you for assisting beautifully in the process! I love your boxers!!! Kiss them for me. Also, a recent blog entries shows pics of my future GSD puppy. http://www.foodshethought.com

Thank you so much for the great explanations. I have been using a point and shoot to photograph my pictures for my blog, but I know the time hascome to move to the next step. Do you have any recommendations for a first “good” camera , without getting something too complicated or expensive?

Very interesting but still confusing at the moment. You’re absolutely right that taking photos takes practice. I did try adjusting the aperture with a higher number. but then I also have to adjust the shutter speed, because if I don’t, I would get a really dark photo. That’s what is confusing me sometimes. And there are also times that I don’t have a good, bright light. Well, I need to start practicing and see the difference. Thank you so much for sharing this.

Divina- It sounds like you are shooting full manual right now, which can be very challenging. Try using the Aperture Priority mode first, and let the camera make the other adjustments to get a decent exposure. That way you can see how changing the aperture affects your depth of field and you can start to control aperture to make creative decisions with your photos.
And remember that you can only shoot within the parameters of the lens that is on your camera.

Wow! Once again, another amazing post. This one I’m going to have to read, and read again. You’re right, it IS confusing, but I think your plain-english explantions are going to help me “get” it. Thanks again for taking the time to put these post together.

This is an amazing series. Even though many of these things have been told to me before, seeing the picture illustrations, along with your very clear explanations is helping me to understand it a lot better. Thank You!